Selecting the correct shredder capacity for a tyre recycling facility is a critical engineering decision that dictates long-term operational efficiency, energy consumption, and overall plant profitability. Sizing a shredder involves more than simply matching a target tonnage number; it requires a rigorous evaluation of mechanical parameters, feedstock characteristics, duty cycles, and downstream processing requirements.
An analytical framework for sizing and selecting industrial tyre shredder capacity involves several distinct evaluation stages, such as:
Feedstock Variability and Material Density
The physical properties and composition of the incoming tyres dictate the necessary cutting force, torque thresholds, and chamber geometry. Feedstock is typically categorized into three distinct classes:
- Passenger Car Tyres (PCR): Characterized by lower weight, thinner rubber walls, and lower steel-to-rubber ratios. They offer higher volumetric reduction rates and lower resistance, allowing machines to achieve higher throughputs per kilowatt-hour.
- Truck and Bus Tyres (TBR): These feature significantly heavier sidewalls, dense tread depths, and substantial high-tensile steel bead wires. Processing TBR requires higher torque profiles and robust, heat-treated alloy cutters to prevent premature wear and mechanical stress.
- Off-The-Road (OTR) Tyres: Massive industrial and earthmover tyres present unique engineering challenges. Due to their immense diameters, thick treads, and heavy structural steel components, OTR tyres necessitate specialized primary shredders with wide cutting chambers and extreme torque capacities.
Engineering Implication: If a facility processes a mixed feedstock stream, the shredder must be engineered to handle the maximum resistance load of the toughest material (typically TBR or OTR) rather than the mathematical average of the weight mix.
Calculating True Throughput (TPH vs. Operational Efficiency)
Throughput is universally measured in Tonnes Per Hour (TPH), but a common pitfall in plant design is confusing theoretical peak capacity with sustainable operational capacity.
When calculating required TPH, tyre recycling plant operators must account for several operational realities, like:
- Effective Operating Time: Continuous feeding is rarely achievable in practice due to material handling cycles, loader feeding pauses, and routine maintenance windows.
- The Safety Buffer: Systems should ideally be specified with a 15% to 20% capacity margin. Running a shredder at 100% continuous peak load accelerates thermal buildup in the drive components and increases mechanical fatigue.
- Duty Cycle Demands: A facility operating a single 8-hour shift has different thermal and mechanical dissipation requirements than a plant running a continuous 24/7 duty cycle, which necessitates heavy-duty cooling systems and easily serviceable wear parts.
Downstream Processing and Granulation Constraints
The required output size directly influences the capacity flow of the entire recycling line. Tyre recycling plants typically operate in 3 stages, such as:
- Primary Shredding
Fornnax SR-Series Primary Shredders perform the initial volume reduction of end-of-life tyres, producing uniformly sized tyre strips/shreds ranging from 50 to 150 mm.
- Secondary Shredding
The primary tyre shreds are then fed into the Fornnax R-Series Secondary Shredder, which further reduces the material to 20–30 mm tyre chips, commonly referred to as rubber mulch. This stage facilitates the liberation of ferrous metal from the bead and tread areas, producing rubber mulch that is up to 98% steel-free for further processing. At this stage, the material can be marketed as high-quality, low-steel Tyre-Derived Fuel (TDF) for various combustion applications or processed further through granulation.
- Granulation
In the granulation stage, the 98% steel-free rubber mulch is fed into the Fornnax TR-Series Granulator, which is specifically designed to process steel-free rubber chips for further size reduction and textile liberation. The process separates the textile fraction and produces rubber granules in the 0.8–4 mm size range.
Power Dynamics: Low-Speed, High-Torque (LSHT) Principles
Unlike high-speed hammer mills used in other recycling sectors, industrial tyre shredders rely on Low-Speed, High-Torque (LSHT) shearing technology.
- Torque vs. RPM Balance: High torque allows the machine to cleanly fracture thick rubber and shear through high-tensile steel bead wires without stalling.
- Motor Sizing: The installed motor power (kW/HP) must be precisely matched to the gearbox reduction ratio and shaft geometry. An underpowered motor will experience frequent RPM drops under heavy shock loads, triggering automated auto-reversal sequences that reduce net hourly throughput and increase energy waste.
Scalability and System Modularity
Recycling markets fluctuate, and facility inputs often shift over time based on regional supply and regulatory changes. When designing a plant layout, future-proofing capacity is vital. Modular system architectures allow operators to install a high-capacity primary shredder capable of managing future volume expansion, while initially investing only in the downstream separation modules required for current market demands.
Proper capacity selection balances mechanical stress limits, feedstock variations, and downstream processing bottlenecks to ensure stable, long-term plant performance.
Choosing the Right Shredder Capacity for Your Tyre Recycling Plant
Selecting the right shredder capacity is not simply about choosing a machine based on tonnes per hour. It requires a detailed assessment of your tyre mix, operating hours, desired output size, downstream equipment, power requirements, and future capacity needs.
The right capacity ensures that your shredder operates efficiently without becoming a bottleneck for the rest of the recycling line.
If you are planning a new tyre recycling plant, upgrading an existing line, or evaluating the right shredding capacity for your feedstock, the Fornnax team can guide you through the selection process. Our technical experts can assess your tyre mix, throughput requirements, output specifications, and downstream processing needs to help you identify a shredding solution designed for reliable and efficient long-term operation.